Convergence of the Adaptive-Wall Wind Tunnel

Analytical functional relationships for exterior and interior regions with respect to the control surface inside a two-dimensional wind tunnel are used to investigate the iteration procedure for an adaptive-wall wind tunnel. Convergence to interference-free conditions is proven for any symmetric model in subsonic flow. Also, formulas are presented for determining interference-free conditions directly from two measured flow variables at the measuring plane, thus enabling an adaptive-wall wind tunnel to achieve unconfined flow in a single adjustment. A wavy-wall model and an NACA 0012 airfoil are used as examples to examine the convergence and validate the derivation. In addition, a numerical solution to the transonic small disturbance equation is used to demonstrate the convergence of the adaptive-wall iterative procedure for supercritical flow on an airfoil.